1. Field of the Invention
The present invention relates to a sheet conveying device and more particularly to a sheet conveying device including a unique mechanism for switching a sheet conveying path, a sheet processing apparatus including the sheet conveying device, an image forming apparatus including the sheet processing apparatus, an image forming system including the sheet processing apparatus, a computer program for controlling the sheet conveying device or the sheet processing apparatus, a computer program for executing a sheet processing method with a computer, a recording medium storing such a computer program such that a computer can read it out, and a sheet processing method.
2. Description of the Background Art
Japanese Patent Laid-Open Publication Nos. 7-315668 and 2000-53302, for example, each disclose a sheet conveying device in which path selectors are positioned in parallel in a direction of sheet conveyance. This configuration minimizes the widthwise dimension of the path selectors for thereby reducing the overall size of the sheet conveying device.
Particularly, in the sheet conveying device taught in the above Laid-Open Publication No. 7-315668, two path selectors do not pivot independently of each other, but pivot at the same time as each other. Such path selectors, however, occupy a great exclusive area when pivoting and cannot pivot at the same time unless use is made of solenoids having great power.
On the other hand, the sheet conveying device taught in Laid-Open Publication No. 2000-53302 includes path selectors respectively positioned at a first and a second branch portion and interconnected by a first, a second and a third link member and solenoids that control the links to switch a sheet path. Further, a third path selector is positioned at the second branch portion and driven independently of the second path selector about its own fulcrum. This configuration has a problem that when the edge of the upper path selector contacts the upper surface of the lower path selector when selecting an upward path, the above edge and the edge of the lower path selector are apart from each other by a great distance. As a result, it is likely that the leading edge of a sheet being conveyed abuts against the upper surface of the lower path selector and is steed downward thereby instead of being steered upward by the edge portion of the upper path selector, resulting in a jam.
As stated above, arranging path selectors in parallel is one of effective implementations for reducing the overall size of a sheet processing apparatus. However, a problem with the conventional technologies is that a particular solenoid or drive source must be assigned to each of two path selectors arranged in parallel and rotatable independently of each other, increasing the cost of the sheet processing apparatus. Moreover, the solenoids each being assigned to a particular path selector obstruct the reduction of the size, particularly width, of the sheet processing apparatus.